It can be set independently per station. As an example, in Norway the NRK Jazz channel transmits at 64 kbit/s, while NRK Klassisk (classical music) transmits at 96 kbit/s.
Unfortunately this doesn't improve sound quality because stations use the extra efficiency to switch to lower bit-rates.
Some countries have stations at 48kbps. The UK is leading the drive to lower sound quality with DAB+ stations on the SDL multiplex at 32kbps.
Note that DAB+ also hides a cost increase because stations have to pay Fraunhofer for its patents. Fun, isn't it? ;-)
Fun it is, considering that money goes all back to Germany! insert evil German laugh here